Hi David~
Sorry it took a bit to get back to you.
Yes, my Aunt obtained documented proof back in 1988 in order for us to get registered & receive our Indian cards. I'm embarrassed to say, however, the rest of my family were only interested in the benefits of a card. Thus, they passed the documents around from cousin to cousin like a Sunday's paper coupon. The last relative known to have the documents died in the early 1990's, and no one knows where they are. Nor do they care as long as they have their "card". So, the documentation is out there and can be had again I'm sure.